A DC/DC converter has a comparator that compares a fraction of the output voltage of the converter with a reference voltage and applies an enable signal to the converter power stage when the output voltage is lower than the reference voltage. In response to the enable signal, the power stage of the converter supplies conversion pulses to a load. At high switching frequencies, the propagation delay of the comparator increases with decreasing input overdrive (the voltage difference between the positive and negative inputs). When the propagation delay becomes longer than the switching period, the converter can no more react in the same cycle, and an additional conversion pulse is produced. As a result, multiple conversion pulses (bursts) are produced instead of single pulses. This substantially increases the output voltage ripple. A rough calculation of the output voltage ripple shows that it cannot be smaller than the product of the comparator's overdrive voltage needed for a propagation delay equal to the switching period and the attenuation factor of the resistive divider at the output of the converter power stage:                Vripple>V(overdrive @ tcycle)*Attenuation factor.        
The resistive voltage divider at the output of the converter power stage may have parasitic capacitances which introduce further delay in the feedback loop.
In addition, with inductive boost converters, a delay is produced inherently since energy is transferred to the output in the OFF period of the power stage (in the ON period, the inductor is charged). As a consequence, the output voltage will normally decrease during the first part if the conversion cycle (the ON period), and the comparator has a shorter time left to react.
These phenomena separately and in conjunction cause pulse bursts to occur at the output of the power stage instead of single pulses, thereby introducing output voltage ripple.